Fibre optic monitoring installation and method

ABSTRACT

The invention relates to installations for fiber optic monitoring of articles, and apparatus and methods for forming such installations, including a modular system and components for forming a fiber optic monitoring installation. Applications of the invention include the monitoring of vessels, chambers, and fluid conduits in industrial processing plants, and the invention has particular application to monitoring large vessels, for example temperature monitoring of vessels used in catalytic reforming processes. Convenient installation on or removal from the article being monitored is achieved by providing a support structure for the fiber optic length, which presents the fiber optic length in a preconfigured orientation suitable for monitoring the article. In a particular embodiment of the invention, the fiber optic length is disposed on a panel in a plurality of dense spiral patterns.

CROSS-REFERENCE TO RELATED APPLICATIONS

This application is a continuation application of U.S. patentapplication Ser. No. 13/884,235, having a filing date of Oct. 29, 2013.U.S. patent application Ser. No. 13/884,235 is a U.S. National Phaseapplication of International Application No. PCT/GB2011/052176, whichfiled on Nov. 8, 2011. International Application No. PCT/GB2011/052176claims priority to GB Patent Application No. 1018802.7.

The invention relates to installations for fibre optic monitoring ofarticles, and apparatus and methods for forming such installations.Aspects of the invention relate to a modular system for forming a fibreoptic monitoring installation and components thereof. Applications ofthe invention include the monitoring of vessels, chambers, and fluidconduits in industrial processing plants, and the invention hasparticular application to monitoring large vessels. Particular of theinvention are concerned with the temperature monitoring of vessels usedin catalytic reforming processes.

BACKGROUND TO THE INVENTION

The background to the invention will be described in the context ofcatalytic reforming processes, although the invention is not so limitedand has application to a variety of industrial processes in whichmonitoring of plant equipment, including vessels, chambers and fluidconduits, is beneficial. It will be apparent that the invention isparticularly useful in industrial applications which use large vesselsor chambers for containing fluids and/or feedstocks during reactionprocesses.

Catalytic reforming processes are used to increase the octane ratings ofpetroleum refinery feedstocks to form into high octane liquid products,and are utilised during the generation of the majority of the world'sgasoline. A number of catalytic reforming processes have beendevelopment since 1940s, all of which use platinum and/or rheniumcatalysts. Examples include the proprietary Platforming processdeveloped by Universal Oil Products; the Rheniforming processproprietary to Chevron Oil Company; the Powerforming process proprietaryto ExxonMobil; and the proprietary Ultraforming process of BP. A typicalcatalytic reforming process takes place in a large cylindrical vessel ofapproximately 2 to 4 meters in diameter, and is a continuous processwhich takes place at a temperature of around 400° C. to 600° C. FIG. 1shows a typical vessel 10, having a cylindrical outer wall 12, orientedvertically on a concrete support 14 which surrounds a lower part 16 ofthe vessel.

In order to prevent heat losses and to preserve the external wall of thevessel 10, a stainless steel liner is fitted on the interior wall of thevessel, with a layer of insulating material between the inner and outerwalls. During normal operation, the typical temperature of the outerwall is around 180° C. Over its lifetime, the interior stainless steelliner can be damaged, which may allow leakage of the hot reactants intothe insulation layer. This exposes the outer wall to high temperatures,and the inside surface of the outer wall to hydrogen. “Hot spots”develop on the vessel surface. In the presence of the hot spot, HighTemperature Hydrogen Attack (HTHA) can lead to severe local weakening ofthe structure. Conventionally, hot spots have been detected through achange in colour of heat sensitive paint applied to the outer surface ofthe vessel. Typically, this will change colour at temperatures above200° C. and provide a visual indication 18 of a hot spot.

For many industrial installations, visual inspection by the use of heatsensitive paints is inadequate for the monitoring of the condition ofthe vessel. Firstly, the heat sensitive paint does not provide anyquantitative data about the maximum temperature that has been reached.Secondly, the geometry of the installation in the vessel often meansthat visual inspection is not possible. For example, many catalyticreforming process vessels have a concrete support which obscures visualinspection of the vessel, of the type shown in FIG. 1.

More recently, it has been proposed to provide temperature monitoring ofcatalytic reforming process vessels by using fibre optic DistributedTemperature Sensor (DTS) systems. An example of a distributedtemperature sensor is described in GB 2239310. Another example of asuitable DTS system is the applicant's proprietary system marketed underthe ULTIMA trade mark.

In a typical application of a fibre optic monitoring system, the fibreoptic is wrapped around the outer surface of a vessel in a continuouslength, to provide a suitable surface distribution for monitoring thetemperature of the vessel. However, to date this approach has beenlimited to the exposed parts of the vessel; the surface of the vesselwhich is beneath structural elements such as the concrete support 14 isunable to be monitored due to installation difficulties.

Other disadvantages of the previously proposed systems are apparent. Inparticular, installing the fibre optic on the surface of the vessel bythe conventional methods can only be performed during process shutdowns.The installation method is also time consuming and labour intensive.Conventional installation methods also have an unacceptable risk ofmechanical damage to the cable. Furthermore, this type of installationis not well disposed to removal and replacement, which may be necessaryto allow inspection and repair of the vessel, or to replace amalfunctioning or damaged fibre optic length.

It is amongst the aims and objects of the invention to provide a fibreoptic monitoring Installation, apparatus and/or method which overcomesone or more drawbacks and deficiencies of the presently availableapparatus and methods.

Additional aims and objects of the invention will become apparent fromthe following description.

SUMMARY OF THE INVENTION

According to a first aspect of the invention, there is provided a fibreoptic monitoring installation comprising:

an article having an outer surface to be monitored;

a fibre optic support structure arranged to support a fibre optic lengthin a predetermined orientation which corresponds to a part of a surfaceof an article to be monitored;

means for locating the fibre optic support structure in relation toarticle such that, in use, the fibre optic length is sensitive to acondition of the surface of the article; and

fibre optic instrumentation coupled to the fibre optic length.

A predetermined orientation shall be taken to include an orientation,arrangement, configuration and/or pattern by which the fibre opticlength is capable of facilitating measurement of a condition of thesurface of the article such as, for example, described in relation tothe preferred embodiments.

By providing a support structure for the fibre optic length, the fibreoptic length may be attached to the support structure in a preconfiguredorientation suitable for monitoring the article. This enables convenientinstallation on or removal from the article. The fibre optic length ispreferably attached to the support structure before the supportstructure is located in relation to the article to be monitored.However, in another embodiment the support structure may be configuredto be located in relation to the article to form an in situ support forsubsequent installation of the fibre optic length.

The support structure may define a monitoring area, which may correspondto a part of the article, and the fibre optic length may be arranged ina preconfigured pattern or orientation over the area defined by thesupport structure.

Preferably, the installation comprises at least one module, the modulecomprising the fibre optic support structure, and a fibre optic lengthsupported by the support structure in a predetermined orientationcorresponding to a part of a surface of the article. The supportstructure may for example be a preformed conduit or channel forreceiving a fibre optic length, or may be a sleeve. The supportstructure may be a mesh panel. However, in one preferred embodiment, thesupport structure is a frame.

In another preferred embodiment, the support structure is a panel, inwhich case preferably the panel comprises a plurality of guide portionson a surface thereof to arrange the fibre optic length in thepredetermined orientation. Preferably, the guide portions are arrangedto arrange the fibre optic length in a plurality of fibre spiralpatterns. Preferably, the panel comprises a plurality of apertures toallow the fibre to pass to another surface of the panel, for examplebetween successive fibre spiral patterns. Preferably, the panel furthercomprises attachment means to hold the fibre optic length in thepredetermined orientation.

Where support structure may be configured to be installed on the articleto be monitored, and to subsequently receive the fibre optic length insitu on the article. The support structure may be configured as a sleeveor helical structure on the article.

The support structure may be configured to be installed on the articleto be monitored, and to subsequently receive the fibre optic length insitu on the article.

Preferably the installation comprises a plurality of modules, eachmodule comprising a fibre optic support structure and a fibre opticlength. The installation may comprise means for locating the pluralityof modules such that the fibre optic lengths are presented to thesurface of the article. The invention may therefore provide a modularsystem, which facilitates installation at or on an article to bemonitored. The shape and form of the modules, the number of modules andthe manner in which they are arranged at or on the article, may beselected according to the type and shape of the article. Each module maytherefore monitor a zone or area of the article.

In one embodiment, the installation comprises a plurality of modules ofsubstantially the same shape and/or as one another. Therefore themodules may be interchangeable. Each module may correspond to a part ofthe shape of the article. For example, the article may be cylindrical,and the modules may be part-cylindrical such that together they form asubstantially cylindrical shape.

The article may be a part of an industrial process facility, and maycomprise a chamber or fluid conduit. In preferred embodiments of theinvention, the article is a vessel, and it may have a substantiallycylindrical outer surface. The invention has particular benefits formonitoring large articles. Where the article is a vessel, it may have adiameter greater than 1 meter, and may for example have a diameter inthe range of 1 meter to 10 meters. The Invention is particularlysuitable for vessels having a diameter in the range of 2 to 4 meters,such as those used in catalytic reforming processes in the petroleumindustry and in a particular embodiment, the vessel is a catalyticreforming process vessel. However, it will be appreciated that theprinciples of the invention can be applied to vessels of other shapesand size.

The installation preferably comprises a fibre optic loop coupled to thefibre optic instrumentation, and one or more fibre optic lengths coupledto the fibre optic loops. Preferably, a plurality of fibre optic lengthsis coupled to fibre optic instrumentation, and most preferably at leasttwo of the plurality of fibre optic lengths is connected in series in afibre optic circuit.

Preferably, the fibre optic instrumentation is coupled to the loop atboth ends of the loop. This permits operation of system even if a partof the fibre optic becomes broken. In addition, it enables individuallengths to be removed from the installation without affecting theoperation of the remaining modules. This enables modules to be replacedand/or repaired, and also allows a module to be removed for visualinspection of the article while fibre optic monitoring continues to takeplace via other modules (which remain connected to the fibre opticinstrumentation).

The installation may comprise means for connecting one or more of theplurality of modules together. At least one module may comprise aconnector for connecting to an adjacent module. The connector may form apart of the module, and preferably forms a part of the frame.

In a preferred embodiment, the installation comprises means fortensioning the support structure against the article to be monitored.The installation may comprise a plurality of modules tensioned togetherto locate the modules at or on the article.

The installation may comprise a mechanism for clamping the modules. Themodules may be clamped to one another and/or maybe clamped to thearticle. Preferably, the installation comprises one or more clampingassemblies configured to locate the plurality of modules such that theirrespective fibre optic lengths are presented to the surface of thearticles.

In one embodiment, the clamping assembly comprises a pivoting clampassembly, configured to engage with formations on frames of the modules.The pivoting clamp assembly is preferably operable to engage withformations on the frame to bring adjacent frames together, and/or toimpart tension to the installation.

The fibre optic monitoring instrumentation may be a distributedtemperature sensor (DTS) instrument. Alternatively or in addition, thefibre optic instrumentation may comprise an acoustic monitoring sensorinstrument, and/or a strain or pressure monitoring sensor instrument.

According to a second aspect of the invention, there is provided amethod of forming a fibre optic monitoring installation, the methodcomprising:

providing a fibre optic length in a preconfigured orientationcorresponding to at least a part of a surface of an article to bemonitored;

presenting the preconfigured orientation of the fibre optic length tothe surface of the article; and

coupling the fibre optic length to fibre optic monitoringinstrumentation.

The fibre optic length may form part of a first module, the first modulecomprising a first frame, wherein the fibre optic length is supported bythe frame.

Preferably, the method comprises the steps of providing a fibre opticsupport structure, and arranging the fibre optic length on the supportstructure in a predetermined orientation which corresponds to a part ofa surface of the article. In a preferred embodiment, the methodcomprises arranging the fibre optic length on the support structureprior to its presentation to the surface of the article. However, inembodiments of the invention the method may comprise the steps ofproviding a support structure on the article and subsequently attachingthe fibre optic length to the support structure. The method may includearranging the fibre optic length on the support structure so as to forma plurality of fibre spiral patterns.

The method may comprise the step of clamping the support structure andfibre optic length against the article. The method may comprisetensioning the support structure and/or fibre optic length against thearticle.

Embodiments of the second aspect of the invention may include one ormore features of the first aspect of the invention or its embodiments,or vice versa.

It will be appreciated that the invention extends to constituent partswhich are used in the above-described installation and methods.Therefore according to a third aspect of the invention, there isprovided a kit of parts which, when assembled, forms a fibre opticmonitoring installation, the kit of parts comprising:

a plurality of fibre optic support structures, each support structureconfigured to support a fibre optic length in an orientationcorresponding to a part of a surface of an article to be monitored;

a plurality of fibre optic lengths, each configured to be supported onone of the plurality of frames, and configured to coupled to fibre opticmonitoring instrumentation.

The kit of parts may further comprise fibre optic monitoringinstrumentation, which may be a distributed temperature sensorinstrument.

Embodiments of the third aspect of the invention may include one or morefeatures of the first or second aspects of the invention or itsembodiments, or vice versa.

According to a fourth aspect of the invention, there is provided amodule for a fibre optic monitoring installation, the module comprising:

a first fibre optic length operable to be coupled to fibre opticmonitoring instrumentation;

a first support structure configured to support the first fibre opticlength in an orientation corresponding to at least a part of a surfaceof an article to be monitored;

means for locating the first support structure such that the firstlength of fibre optic is presented to the surface of the article.

Preferably, the module is configured to be attached to second and/orfurther modules, to together form a fibre optic monitoring installation.One or more of the second and/or further modules may comprise a fibreoptic length operable to be coupled to fibre optic monitoringinstrumentation; a frame configured to support the fibre optic length inan orientation corresponding to at least a part of a surface of thearticle to be monitored; means for locating the support structure suchthat the length of fibre optic is presented to the surface of thearticle.

Embodiments of the fourth aspect of the invention may include one ormore features of any of the first to third aspects of the invention orits embodiments, or vice versa.

According to a fifth aspect of the invention, there is provided anapparatus for a fibre optic monitoring installation, the apparatuscomprising:

a frame configured to support a fibre optic length in an orientationcorresponding to at least a part of a surface of an article to bemonitored;

means for locating the frame such that a supported fibre optic ispresented to the surface of the article.

Embodiments of the fifth aspect of the invention may include one or morefeatures of any of the first to fourth aspects of the invention or itsembodiments, or vice versa.

According to a sixth aspect of the invention, there is provided a methodof monitoring the temperature of a catalytic reforming process vessel,the method comprising:

providing a fibre optic monitoring installation on the vessel, theinstallation comprising a plurality of modules each having a supportstructure and a fibre optic length supported by the support structure inan orientation corresponding to a part of an outer surface of thevessel;propagating light in at least one of the fibre optic length; andcollecting data from the fibre optic monitoring installation at adistributed temperature sensor receiver.

The method may comprise processing the collected data to provide adistributed Temperature map of the vessel.

Preferably, the method comprises generating a signal in response to thedetection of an undesirable temperature condition of the vessel. Thesignal may comprise a visual and/or audible warning signal.

The method may comprise recording a time series of the collected data.

Preferably, the method comprises collecting data from one or more fibrespiral patterns of the fibre optic length and processing the data as ifreceived from a corresponding number of point sensors.

Embodiments of the sixth aspect of the invention may include one or morefeatures of any of the first to fifth aspects of the invention or itsembodiments, or vice versa.

According to a seventh aspect of the invention, there is provided amethod of forming a fibre optic monitoring installation, the methodcomprising:

providing a fibre optic support structure in a preconfigured shapecorresponding to at least a part of a surface of an article to bemonitored;

attaching a fibre optic length to the fibre optic support structure suchthat that the fibre optic length is in an orientation corresponding toat least a part of a surface of an article to be monitored;

locating the combined fibre optic length and support structure at thearticle to be monitored such that in use, the fibre optic length issensitive to a condition of the to the surface of the article; and

coupling the fibre optic length to fibre optic monitoringinstrumentation.

Embodiments of the seventh aspect of the invention may include one ormore features of any of the first to sixth aspects of the invention orits embodiments, or vice versa.

BRIEF DESCRIPTION OF THE DRAWINGS

There will now be described, by way of example only, various embodimentsof the Invention with reference to the drawings, of which:

FIG. 1 is a perspective view of a typical vessel used in a catalyticreforming process;

FIG. 2 is a side view of a module according to an embodiment of theinvention;

FIG. 3 is a schematic view of a fibre optic monitoring system accordingto an embodiment of the invention;

FIG. 4 is a perspective view of a fibre optic monitoring installationaccording to an embodiment of the invention;

FIG. 5 shows an initial installation step according to an embodiment ofthe invention;

FIG. 6A to 6C show schematically steps of an installation methodaccording to an embodiment of the invention;

FIG. 7 shows schematically a step of an installation method according toan alternative embodiment of the invention;

FIGS. 8A to 8B show schematically steps of an installation methodaccording to an alternative embodiment of the invention;

FIG. 9A is a perspective view of a fibre optic monitoring installationaccording to an alternative embodiment of the invention;

FIG. 9B is an enlarged view of the support structure of the embodimentof FIG. 9A;

FIG. 10A is a perspective view of a fibre optic monitoring installationaccording to an alternative embodiment of the invention;

FIG. 10B is an enlarged view of the support structure of the embodimentof FIG. 10A; and

FIG. 11A is a side view of a module according to an alternativeembodiment of the invention.

FIG. 11B shows a cross-section through line X of FIG. 11A according toan alternative embodiment of the invention.

FIG. 11C shows an enlarged view of a portion of one of the spirals inFIG. 11A according to an alternative embodiment of the invention.

DETAILED DESCRIPTION OF PREFERRED EMBODIMENTS

Referring firstly to FIG. 1, there is shown generally depicted at 10 acatalytic reforming process vessel having a cylindrical outer wall 12.The vessel 10 is oriented vertically on a concrete support 14 whichsurrounds a lower part 16 of the vessel. An annular space 19 of a fewcentimeters (3 to 10 cm) is provided between the concrete support 14 andthe outer wall 12. However, the concrete support 14 prevents visualassessment of the vessel, and restricts manual access to the lower part16 of the vessel.

FIG. 2 shows generally at 20 a module forming a part of a firstembodiment of the invention. The module 20 is suitable for use as acomponent of a fibre optic monitoring system for the vessel 10. Thisembodiment of the invention is suitable for a wide range of industrialapplications, and includes benefits in installation, removal, andmonitoring inaccessible surfaces of the vessel.

The module 20 comprises a fibre optic length 21 supported by andattached to a support structure in the form of frame 22. The frame 22 isformed from a panel 23 of a thermally conductive metal material (forexample stainless steel, aluminium or an alloy thereof). The panel 23has preformed windows 24 between horizontal and vertical members 25, 26.Edges of the frame 22 comprise corresponding attachment features 27, 28which are configured to attach the module 20 to an adjacent module (notshown) or other attachment feature of the installation. The fibre opticlength 21 is attached to the frame 22 by attachment points 29 spacedalong the frame, and follows a convoluted path over the areal extent ofthe frame to define a monitoring area. It will be appreciated that thepattern followed by the fibre optic length 21 can be varied according tothe application (such as in the alternative embodiment shown in FIGS.11A-11C and described in further detail below).

In this embodiment, the module is pre-assembled from the frame and thefibre optic to allow easy installation on the vessel 10. The frame 20 isplanar, but has sufficient flexibility and compliance to allow it to becurved around the outer surface of the vessel. In alternativeembodiments, the frame may have an intrinsic curvature to match theshape of the vessel.

Ceramic insulating material (not shown) is placed between the fibreoptic cable 21 and the frame 23 to insulate the fibre optic from theeffects of the environment.

FIG. 3 shows schematically a fibre optic monitoring system 30 comprisingmultiple modules 20′. The modules 20′ are similar to modules 20, andwill be understood from FIG. 2 and the accompanying description. Themodule 20′ differs from the module 20 in the layout of the frame and theorientation of the fibre optic length, but functions in the same way.The system 30 comprises multiple (in this case four) modules 20′ which,each of which define a monitoring area. In use, the modules 20′ arelocated against the surface of the vessel 10 to be sensitive to acondition of the vessel 10. The system 30 is configured as a DistributedTemperature Sensor (DTS) system for monitoring the temperature of theouter wall of the vessel 10, and the fibre optic lengths 21′ areselected for high temperature operation. The system 30 comprises a DTSinstrument 31 located remote from the vessel 10 in a control room (notshown). A surface cable 32 with a multiple fibre optic core is routedfrom the control room to the vessel 10. The surface cable 32 is selectedto meet fire and safety standards.

The ends of the fibre optic lengths 21′ are connected in series bysplicing them together in a junction box 33 via interconnecting cable 34to form a loop. The interconnecting cable 34 is protected by a metaltube (not shown) to provide additional protection during routinemaintenance work. Access to both ends of the fibre optic lengths 21′ isprovided by splicing the two ends of the loop to two separate fibres inthe surface cable 32.

An optical switch 35 is incorporated at the optical output of the DTSinstrument 31 which enables the monitoring of the fibre loop from bothends. This has two advantages. The first advantage is that thetemperature accuracy can be improved by combining the two measurements.The second advantage is that the whole length of the fibre can bemonitored if there is a break in the fibre.

Although the system 30 is configured for monitoring one vessel 10, thesystem can be extended to monitor additional vessels. For example, thefibre optic lengths of additional modules may be spliced in series withthe fibre optic lengths 21′ to form a part of the loop. Alternatively,they may be routed separately back to the DTS instrument via additionalfibres in the surface cable 32, used in conjunction with a multichanneloptical multiplexer (not shown) to sequentially monitor the additionalvessels.

FIG. 4 shows the system 30 in a fibre optic monitoring installation 40on a vessel 10. The installation 40 comprises four modules 20 installedon the vessel 10, in the annular space 10 between the vessel 10 and theconcrete support 14. The modules 20 are arranged to present theirrespective fibre optic lengths to the surface, such that they aresensitive to the temperature conditions of the vessel. Each module canbe installed individually on the vessel to cover a monitoring area orzone. The modules 20 are connected together by connectors 41 and placedunder tension to ensure good thermal conduct between the fibre and thevessel and accommodate thermal expansion and contraction of the vessel.Examples of installation methods are described in more detail below.

In use, the system monitors the surface of the vessel 10 to providequantitative temperature data. The installation 40 also optionallycomprises a visual and audible indicator 42 which is activated inresponse to the detection of an undesirable temperature condition. Whena hotspot is detected an alarm signal is sent to the local indicator 42via the surface cable to draw immediate attention to the detectedcondition. The surface cable may therefore be a hybrid electrical andoptical cable. In an alternative embodiment the warning signal may betransmitted optically, which is advantageous if it is undesirable toprovide electrical cables in the vicinity of the vessels.

Methods of forming the monitoring installation 40 will now be described.The frames allow convenient installation of the system on parts of thesurface which are difficult to reach due to the geometry of theinstallation. However, it will be appreciated that the invention alsohas benefits when the modules are installed in accessible areas of thevessel, including ease of installation and removal. Furthermore, theinvention allows the system to be installed and/or removed withoutinterrupting the operation of the vessel.

In the embodiment of FIG. 4, lower part of the vessel beneath theconcrete support is more accessible from below than from above. Theindividual modules are pre-assembled, and are positioned against thesurface of the vessel by raising the modules up into the annular spacebetween the concrete support 14 and the vessel from below. FIG. 5 showsan initial stage of installation, in which a module 20′ is verticallysupported in the annulus by a bracket 52. The bracket 52 is an“L-shaped” bracket fitted to the concrete support (not shown in FIG. 5),and comprises a pin 53 which supports the module 20′ vertically in thespace. Additional modules are positioned against the surface of thevessel sequentially around the vessel, and supported vertically bysimilar brackets.

FIGS. 6A to 6C show schematically a mechanism by which the system isinstalled according to one embodiment. For clarity, these drawings showa pair of frames 54 a, 54 b which make up a pair of modules, with thefibre optic lengths omitted and outside of the installation 40. It willbe appreciated that same mechanism may be used in the annular spacebetween the vessel and the concrete support.

Each frame 54 a, 54 b comprises connector formations 56 along opposingadjacent edges 55 a, 55 b. The formations 56 are located along the edgesand extend from the plane of the frames to form abutment surfaces. Theformations are arranged in corresponding pairs which are designed to bebrought together during installation. As most clearly shown in FIGS. 6Band 6C, a pivoting clamp 58 is located around the formations 56, openedagainst the force of a spring 59. The open ends of the clamp 58 arebrought together to engage the abutment surfaces of the formations 56and bring the edges 55 a, 55 b of the frames together, as shown in FIG.6C. An additional spring 57 connects the lower ends of the clamp 58.

For the installation of the monitoring system 40, the method takes placeinside the annular Space 19 between the vessel and the concrete support14. The frames are located in the annular space and vertically supportedby the brackets 52. The clamp 58 is located in the annular space 19 andpositioned around the formations 56. The ends of the clamp 56 arebrought together to engage the abutment surfaces of the formations 56and bring the edges 55 a, 55 b of the frames together, and an additionalspring 57 connects the lower ends of the clamp 58. The attachmentmechanism applies tension to the modules in the installation to maintaingood physical contact between the fibre optic lengths and the vessel andtherefore maintain sensitivity to the vessel condition. In addition, itallows the modules to be brought together from an access positionlocated above or below the modules, enabling the modules to be assembledover areas which are difficult to reach such as behind structuralelements.

Each of a plurality of modules may be brought together and attached inthe manner described above. Alternatively, some of the modules may bemechanically fixed to one another with only one (or some) of theinterfaces between adjacent modules having a tensioned connection.

Variations to the described embodiment are within the scope of theinvention. In one alternative, the clamp is provided with hooks whichengage with slots in the frames. In another, as shown in FIG. 7, theclamp 68 is a scissor-type clamp with a pivot 69 located part-way alongits length. This arrangement operates similarly to the arrangement ofFIGS. 6A to 6C, although it does not require the clamp to be locatedaround the formations on the frames. Instead, the clamp 68 operated frombelow can be positioned on the outside of the formations on the framesfrom below (as shown in the drawing), and is not required to manipulatedover the uppermost formations. This facilitates positioning of the clampin narrow access areas, and the minimal extent of the clamp above theframes may allow them to be positioned higher up in a restricted space.It will be appreciated that this configuration can be inverted foroperation from above.

A further alternative embodiment is illustrated in FIGS. 8A and 8B. Inthis embodiment, the frames 80 are provided with channels 82 formed bybending the material of the frame. The channels are shaped to receive arod clamp 84, which is inserted into the channels 82 to allow the framesto be positioned in relation to the vessel. After positioning of thepanels, high strength springs 84 are installed around the rods tomaintain the modules under sufficient tension to accommodate for thermalexpansion of the vessel in operation.

FIGS. 9A and 9B show a fibre optic monitoring installation 90 accordingto another embodiment of the invention. FIG. 9A shows the system formedfrom modules 91 a, 91 b, located on the vessel. Each module comprises acustom-fabricated aluminium channel structure 92 welded to supports 93.The channel structure 92, most clearly shown in FIG. 9B, comprises achannel for receiving the fibre optic length 94. The depth of thechannel is less than 50% of the cable diameter to ensure that sufficientfibre is upstanding from the channel to provide good contact with thevessel. The channel structure 92 is shaped to follow the curve of thesurface of the vessel to which it is attached. This allows firm pressureto be applied over the entire surface using L-shaped brackets secured tothe concrete support.

The fibre optic length is secured to the channel structure 92 usingcable ties, which are held in place along the length of the channel bynotches 96. In addition, ceramic insulating material (not shown) isplaced between the fibre optic cable and the channel structure 92 toinsulate the fibre optic from the effects of the environment.

FIGS. 10A and 10B show an alternative embodiment 100 of the invention,in which the support structure for the fibre optic cable is a flexiblesleeve 101 of fibrous material. FIG. 10A shows the installation system100, having a part of the concrete support 14 removed to show the sleeve101 beneath. FIG. 10B shows the sleeve 101 and fibre optic assemblyprior to installation.

The sleeve 101 is approximately 3 to 7 mm thick and supports the fibreoptic length in a preformed orientation. The insulating material of thesleeve reduces the effect of ambient temperature on the monitoringoperation, and also prevents conduction of heat from the vessel to theconcrete support. The internal structure of the sleeve 101 is supportedby a steel mesh (not shown). In order to allow installation behind theconcrete collar, the blanket is fitted around the vessel by opening thesleeve at edges 103 a, 103 b and placing the sleeve around the vessel.The sleeve is positioned vertically on the vessel and the edges 103 a,103 b are attached to one another at points above and below the concretesupport using by spring-loaded attachment mechanisms 104. The mechanismtension the sleeve to maintain close contact between the vessel and thefibre optic lengths.

In FIG. 11A, an alternative module 200 is shown in which a very highdensity of fibre 221 is accommodated on a panel 222. The dashed portions221 b of the fibre 221 indicate where the fibre 221 is passed behind thepanel 222 (via apertures 222 a) to avoid having the fibre 221 physicallycross itself. In this way, a series of dense spirals 230 is able to beprovided without risking the fibre 221 being bent, crushed or otherwisedamaged when, for example, the module 200 is pressed onto a vessel to bemonitored. Of course, a number of alternative patterns may be achievedin this way. FIG. 11B shows a cross-section through line X illustratingthe location of the fibre 221 on opposite sides of the panel when in oneof the spirals 230, or behind 221 b the panel 222 between spirals 230.FIG. 11C shows an enlarged view of a portion of one of said spirals 230.

In this particular embodiment, the panel 222 may be pre-shaped tocorrespond, for example, to the shape of a vessel to be monitored suchthat it may be installed directly. Of course, similarly to previouslydescribed embodiments, the panel 222 may be planar and able to conformto the shape of a vessel to be monitored as it is installed.

The front face of the panel 222 (i.e. that facing out of the drawing inFIG. 11A and to the right of the drawing in FIG. 11B and that which isapplied to the vessel surface) is provided with a number of fibre guideportions 229 a which define and arrange the fibre 221 in a spiral pathand a number of attachment points 229 b which hold the fibre 221 inplace. The attachment points 229 b shown herein are short panelpass-throughs corresponding to the spiral path defined by the fibreguide portions 229 a and ensure the fibre 221 is held in thisconfiguration. Alternative attachment points may take the form of clips,studs, loops or other attachment means that would be apparent to theskilled person as suitable for this purpose.

The fibre guide portions 229 a are shown in a concentric orquasi-concentric arrangement, and the attachment points 229 b in aradial arrangement, however the skilled person will readily understandthat a number of variations on and of these arrangements can be employedto effect and maintain a spiral (or other shaped) fibre configuration.

The provision of a series of dense spirals 230 also provides significantmeasurement and processing enhancements. For example, when a DTS isemployed (such as described in relation to FIG. 3) the measurementdensity is vastly increased over previously described moduleembodiments, and the spirals themselves can be treated in processing asan array of virtual point sensors. Similarly, a number of said modules200 may be connected to one another for further enhanced measuring andmonitoring capability.

The invention provides a fibre optic monitoring installation and methodof installation for an article such as a catalytic reforming processvessel. The installation comprises a fibre optic support structurearranged to support a fibre optic length in a predetermined orientation,which corresponds to a part of a surface of the article. The fibre opticsupport structure is located in relation to article such that in use thefibre optic length is sensitive to a condition (such as a temperature)of the surface of the article. Fibre optic instrumentation is coupled tothe fibre optic length. Preferably the installation is a modular systemof modules which allow convenient fitting of the fibre optic lengths tothe article.

The present invention in its various aspects and embodiments offers anumber of advantages over previously proposed fibre optic monitoringinstallations, apparatus and methods. Firstly, the invention allowsconvenient and fast installation and removal of fibre optic lengths byproviding a support structure which orientates the fibre optic in adesired pattern. The invention enables fibre optic installation and/orremoval while an article is in operation in an industrial process, andprotects the fibre optic from mechanical damage.

The invention allows installation of fibre optic lengths overdifficult-to-reach surfaces of an article to be monitored, such as partsof catalytic reforming process vessels which are obscured by structuralelements. The installation methods and apparatus allow tensioning of themonitoring apparatus to maintain good contact between the fibre opticand the vessel (and therefore good sensitivity). Modular systems ofembodiments of the invention facilitate removal and replacement of partsof the monitoring system without interfering with the operation and/ormonitoring of other parts of the article.

Various modifications may be made within the scope of the invention asherein intended, and embodiments of the invention may includecombinations of features other than those expressly disclosed herein. Inparticular it will be appreciated that many features of the variousembodiments of the invention can be interchanged with one another orused in combination in alternative installation designs.

The invention claimed is:
 1. A fibre optic monitoring installation comprising: an article having an outer surface to be monitored; a plurality of modules, each module comprising: a fibre optic length, and a fibre optic support structure arranged to support the fibre optic length, wherein the support structure comprises a frame defining a monitoring area which corresponds to a part of the outer surface of the article, and the fibre optic length is arranged in a predetermined pattern or orientation on a first surface of the frame such that the fibre optic length is located over the monitoring area defined by the frame; means for locating the fibre optic support structure in relation to the article such that, in use, the fibre optic length is sensitive to a condition of the outer surface of the article; and fibre optic instrumentation coupled to the fibre optic length, wherein the installation further comprises a connector for connecting the support structure of each module directly to a support structure of an adjacent module.
 2. The fibre optic monitoring installation according to claim 1, wherein the connector comprises a rod clamp, the frame of each module further comprising a first channel arranged to receive the rod clamp.
 3. The fibre optic monitoring installation according to claim 1, wherein the means for locating the fibre optic support structure in relation to the article is arranged such that, in use, the first surface of the frame faces the outer surface of the article such that the fibre optic length is presented to the outer surface of the article.
 4. The fibre optic monitoring installation according to claim 1, wherein the frame further comprises a plurality of attachment points spaced along the frame for attaching the fibre optic length.
 5. The fibre optic monitoring installation according to claim 1, wherein the frame further comprises a second channel for receiving the fibre optic length.
 6. The fibre optic monitoring installation according to claim 1, wherein the connectors are configured to tension the support structure against the article. 